Triatomine Sexual Behaviour is Mediated by Pheromones

GINA B. PONTES; ANA C.R. DE VITTA; BJÖRN BOHMAN; CLAUDIA A. ZACHARIAS; GABRIEL MANRIQUE; C. RIKARD UNELIUS; MARCELO G LORENZO

Encuentro; I Latin American Meeting of Chemical Ecology; 2010

Triatomine bugs transmit Trypanosoma cruzi, the etiological agent of Chagas disease, to humans. Th is health burden aff ects more than 15 million people in Latin America. We show here that the sexual behaviour of several triatomine species is mediated by pheromones. We characterized a sequence of behaviours that mediate male/female encounters and mating. Furthermore, we identifi ed an assembly of compounds secreted by the metasternal glands (MG) of Triatoma infestans, Triatoma brasiliensis and Rhodnius prolixus, suggesting that they act as sexual pheromones. SPME assays showed that R. prolixus females emit MG odours during the night. In response to these, sheltered R. prolixus males were activated, i.e, left their refuges and showed increased activity. On the other hand, females did not respond to male emitted odours. R. prolixus males presented oriented take-off towards airstreams laden with female odour and this behaviour was triggered by MG signals. Olfactometer experiments revealed that walking T. brasiliensis males choose female odour laden airstreams and female MG secretions were necessary for the expression of this behaviour. Similar results were obtained with R. prolixus males tested on a locomotion compensator. Mating pairs of T. infestans and R. prolixus, known to promote the aggregation of other males, also emitted MG odours. Experiments showed that mating success is drastically aff ected by the occlusion of MGs of R. prolixus males or females. Moreover, the occlusion of female MGs abolished male aggregation. GC-EAD studies determined that several MG compounds promote antennal responses in T. brasiliensis males. In conclusion, we suggest that the volatile blends produced by triatomine MGs act as sexual pheromones. We suggest that MG odours may be used for developing Chagas disease vector detection or capture tools.